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Homework Help: A beam of red light has twice the intensity as a second bean of the same color

  1. May 11, 2008 #1
    1. The problem statement, all variables and given/known data
    A beam of red light has twice the intensity as a second bean of the same color. Calculate the ratio of the amplitude of wave.

    2. Relevant equations
    [tex]intensity \propto (amplitude)^2[/tex]

    3. The attempt at a solution
    [tex]1^{st} \mbox{ beam} = 2I[/tex]
    [tex]2^{nd} \mbox{ beam} = I[/tex]

    I don't know if this step is correct and I don't know what to do next?!
     
  2. jcsd
  3. May 11, 2008 #2
    [tex]I_1=2 I_2[/tex]

    [tex]\frac{I_1}{I_2}=2[/tex]

    What can you do to the above relation (given your relevant equation) to convert it to a ratio of amplitudes?

    Regards,

    Bill
     
  4. May 11, 2008 #3
    [tex]intensity \propto (amplitude)^2[/tex]

    So, it will be [tex]1:4[/tex] ?
     
  5. May 11, 2008 #4

    Defennder

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    Homework Helper

    No, start off by expressing both intensities I = kA^2. Then compare the ratio of each amplitude to the other.
     
  6. May 11, 2008 #5
    No. Try what Defennder suggested to see why.

    Regards,

    Bill
     
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